Our kludgy brain retains this primitive visual structure even though most signals from the eye are processed in the visual cortex, a newer addition. If the latter is damaged, patients typically say they cannot see a thing. Yet if asked to reach for an object, many of them can grab it on the first try. And if asked to judge the emotional expression on a face, they get it right more often than chance would predict—especially if that expression is anger.

This reminds me of a distant relative of a colleague who's been written up in several neurology and speech-pathology journals for a bizarre disability he has following a stroke several years ago. He can clearly hear everything people say to him and repeat it back accurately, but he often has to write their words down (which again is no problem for him) and read it silently to himself before he can actually understand what they said. His ability to interpret music and recognize environmental sounds (doorbell etc.) are unaffected; not sure about his ability to interpret tone of voice. The kind of thing you read about in Oliver Sacks and voyeuristically think, 'Oooh, fascinating!' but wouldn't wish on your worst enemy in real life.

I've always wondered what animals' dreams are like, and how many animals have anything resembling them. It's a bit too easy to get carried away with anthropomorphizing of course, but my dog sure looks like he's having nightmares about being chased, confronting someone or something etc., based on the sounds and movements he makes in his sleep sometimes. (Strangely cats don't seem to display anywhere near as much of this 'behavior', or anywhere near as vigorously, at least in my experience.)

My mother told me about a woman she got to know that had no sense of music anymore.
As some might know, until the 60s in Germany left-handed people were forced to learn to use their right-hand, before they realised that it was crap.
And she was one of these people.
However, this change form being left-handed to be right-handed can have some damage on your brain, and with this woman it was that she would hear music, but not see it as some good music, or bad music. There was no sense of melody anymore.

I've also heard of people that can't see faces. Some weird thing, but they really only see your face, but not the nose, mouth or anything.

It's really an interesting article and nice to know certain things.
And you see how our brain can be tricked. While not reacting to tickling ourselves, because it just ignores this information, we can get tickled by other people or whatever tickles us, and even after we saw that there is something our brain cannot use this information to ignore this tickling as well.

Cats do dream just not as much....they have maintained much more of their wild instincts than dogs...being solitary animals they had to maintain alertness (for prey or foe), therefore they don't drift off into deep sleep to dream. Dogs being orignally social pack animals feel safer to drift off to dream, because they know another dog or a human is going to keep guard as such, allowing them to feel safe.

Hmmm, LJT is that just your own speculation, or is there some precedent in the science of animal behavior for a broad correlation between being a 'highly social animal' and apparently dreaming more? I had the impression that in most species thought to dream, there's more or less a hardwired need for a certain amount of REM sleep (when most dreams occur) and if that 'quota' isn't met, mental health tends to be compromised--with certain exceptions, for example, in humans clinical depression can sometimes actually be helped by reducing the amount of sleep including REM sleep. Of course that's not necessarily incompatible with evolution as a highly social animal (or not); I can see where that might also select for less need for REM sleep--I'd just never heard of that correlation before. Also, I'm unsure as to what extent there's a known connection between observable 'behavior' suggesting dreams and clearly having them--I know my cats don't twitch or flail around in their sleep as much as my dog does, and I've never heard them vocalize while sleeping, but can I assume based on that that they necessarily dream less? They certainly seem to spend as much time sleeping as he does. And is it known that dogs experience more REM sleep than wolves, for example? or lions less than wolves?

The Wikipedia entry on REM sleep mentions this, not sure how much to trust it though, as that article is flagged for inadequate citations:

Quote:

REM sleep occurs in all mammals and birds. It appears that the amount of REM sleep per night in a species is closely correlated with the developmental stage of newborns. The platypus for example, whose newborns are completely helpless and undeveloped, has 8 hours of REM sleep per night; in dolphins, whose newborns are almost completely functional at birth, almost no REM sleep exists after birth.

Yolland, what I said is a bit of my own hypothesis on it, I've never been able to find anything on whether social animals require more REM sleep than solitary ones.

Smaller mammals also require more sleep and as a side affect they get more REM sleep than larger mammals, not through need of REM sleep but just through the need to conserve energy, rats and chimpanzees get about the same amount of REM sleep.

I think the wikipedia article is right though, all mammals and birds seem to have some period of REM sleep except for the Platypus and Echidna I think It does also seem to be related to to immaturity at birth. Cats, dogs etc all have more REM sleep right after birth, where dolphins and horses are bornb able to fend for themselves and have much less REM sleep.